circle mask shader - use these with openGL 2.0

basic testApp.cpp

#include "testApp.h"

//--------------------------------------------------------------
void testApp::setup(){

  
	mPlayer.loadMovie("test_movie.mov");
	
	circleShader.load("circle_mask");
	
	mPlayer.play();
}

//--------------------------------------------------------------
void testApp::update(){
	mPlayer.update();
}

//--------------------------------------------------------------
void testApp::draw(){

	circleShader.begin();
	mPlayer.getTextureReference().draw(ofVec2f(0,0));
	circleShader.end();
}

circle_mask.frag

#version 120
#extension GL_ARB_texture_rectangle : enable

uniform sampler2DRect tex;

void main()
{
	float texWidth=1920.0;  // width in pixels
	float texHeight=1080.0;	// height in pixels
	float edge = 500 / texWidth;	// value in pixels, i.e. circle will have a 500 px radius
	float edgewidth = 10.0 / texWidth;	// value in pixels, i.e. will give you a 10 px blurred edge…

	float heightWidthRatio = texHeight / texWidth;
	
	vec2 normalizedTexCoord = (vec2(gl_TexCoord[0].x / texWidth, gl_TexCoord[0].y / texHeight ) ) - vec2(0.5, 0.5) ;
	normalizedTexCoord.y = normalizedTexCoord.y * heightWidthRatio;
	
	float opacity =  clamp(0.0,1.0,1.0 - smoothstep(edge, edge+edgewidth, (length(normalizedTexCoord))));
	

	gl_FragColor = vec4((gl_Color * texture2DRect(tex, gl_TexCoord[0].xy)).rgb,opacity);
}

circle_mask.vert

#version 120
#extension GL_ARB_texture_rectangle : enable

void main()
{
  gl_FrontColor = gl_Color;
	gl_TexCoord[0] = gl_MultiTexCoord0;
	gl_Position = ftransform();
}

In case someone else ends up trying to use this code as an example, there is a mistake here with the use of clamp. The arguments are in the wrong order. I also had to change the last line.
Here is the last two lines fixed:

    float opacity =  clamp(1.0 - smoothstep(edge, edge+edgewidth, (length(normalizedTexCoord))),0.0,1.0);    
    gl_FragColor = vec4(texture2DRect(tex, gl_TexCoord[0].xy).rgb, opacity);